Make tabs vertical, similar to layers (mockup included)

Overall, I want tabs to be improved, navigation and everything. I had this idea of having tabs in vertical view, similar to layers. It would take up less space and easier to navigate. Mock-up attached.

Tabs are really not good from UX point of view. And there is a lot topics for improving them. Find one and vote up if you have interest. There is some plugin which could be usefull. It tries to solve ugly document tabs: http://creativedo.co/doco